Postoperative subtype P as a risk factor for excessive postoperative sliding of cephalomedullary nail in femoral trochanteric fractures in old patients: A case series of 263 patients using computed tomography analysis

Screening risk factors for the occurrence of wedge effects in intramedullary nail fixation for intertrochanteric fractures in older people via machine learning and constructing a prediction model: a retrospective study

PURPOSE

The wedge effect (V-effect) is a common complication in intramedullary nailing surgery for intertrochanteric fractures and can significantly affect postoperative outcomes. The purpose of this study was to screen risk factors for the intraoperative V-effect in intertrochanteric fractures and to develop a clinical prediction model.

METHODS

A total of 319 patients (77 patients who developed V-effects) from China were randomly divided into a training set (n = 223) and a validation set (n = 96) at a ratio of 7:3. The variables were screened via 3 machine learning methods, including least absolute shrinkage and selection operator (LASSO) regression, the Boruta algorithm, and recursive feature elimination (RFE). Variables that appeared in the three machine learning methods were included in multivariate logistic regression to construct predictive models. Spearman correlation analysis was used to exclude covariance between variables. Restricted cubic splines (RCSs) were used to analyze the relationships among femoral lateral wall thickness, BMI, and the V effect. The differentiation, calibration and clinical applicability of the model were assessed, and the reasonability of the model was analyzed.

RESULTS

Machine learning identified 8 variables that appeared in these 3 machine learning methods, and the covariance between these 8 variables was excluded (r < 0.6). BMI, surgical experience, a lesser trochanteric fracture, the thickness of the lateral wall, the insertion point, bone density, fracture classification, and holiday surgery were found to be risk factors for the occurrence of the V-effect via multivariate logistic regression. The RCS analysis revealed that the lateral wall thickness, BMI, and occurrence of the V effect were linearly related. The final predictive model had good differentiation, calibration and clinical applicability, and it had better predictive efficacy than the other models did.

CONCLUSION

This study employed three machine learning variable selection methods-the LASSO, RFE, and Boruta algorithms-to construct a V-effect predictive model. The model enables orthopedic surgeons to better understand the risk factors associated with the V-effect and provides a reference for surgeons to implement appropriate measures to reduce the incidence of the V-effect.

Elderly trochanteric fracture outcomes: Unveiling the risks of excessive postoperative sliding - A retrospective multicenter (TRON group) investigation

BACKGROUND

Intramedullary nailing (IMN) for femoral trochanteric fractures (FTF) is the primary surgical intervention. Excessive lag screw sliding (ES) of the femoral neck screw sometimes occurs. This multicenter investigation sought to 1) determine the prevalence of ES, 2) evaluate the relationship between ES and postoperative complications, and 3) identify the factors of ES in elderly patients with FTF undergoing IMN.

METHODS

From 2016 to 2020, 1448 patients with FTF were treated using a short IMN across 11 institutions (TRON group). Upon applying exclusion criteria, 519 patients (127 men, 392 women; mean age, 84.4 years) were included. The postoperative sliding distance was measured immediately after surgery and at final follow-up. A sliding distance of ≥8 mm categorized patients as having ES. We identify the factors contributing to ES using the logistic regression analysis, with a p < 0.05 as statistical significance.

RESULTS

ES was observed in 116 patients (22.4 %). Patients with ES had a higher incidence of postoperative cut-out and peri-implant fracture. Logistic regression analysis showed that achieving optimal reduction in both AP and lateral views (odds ratio (OR) 0.48, p = 0.0012) and the use of a double screw system or twin screws with integrated locking mechanism significantly reduced the risk of ES (OR 0.27, 0.17; p = 0.0027, <0.001).

CONCLUSIONS

The incidence rate of ES was 22.4 %. ES was associated with a higher risk of postoperative complications. The surgeons should aim for optimal reduction and use a double screw or twin screws with an integrated interlocking mechanism as the implant of choice.

Insufficient proximal medullary filling of cephalomedullary nails in intertrochanteric femur fractures predicts excessive postoperative sliding: a case-control study

OBJECTIVE

Excessive postoperative sliding is a common complication of intramedullary nails in the treatment of intertrochanteric femur fractures. The aim of this study was to identify risk factors for excessive postoperative sliding in the intertrochanteric fractures treated with an intramedullary nail.

METHODS

A retrospective analysis of 369 patients with femoral intertrochanteric fractures treated with short intramedullary nails between February 2017 and September 2020 was performed. Patients were classified into an excessive sliding group (ES group) and a control group according to the sliding distance after 6 months of follow-up. The proximal medullary filling degree (MFD), fracture reduction patterns in the anteroposterior (AP) view and lateral view, and tip-apex distance (TAD) were evaluated and compared in each group.

RESULTS

Thirty-three cases were included in the ES group, and 336 cases were included in the control group. No significant differences in age, sex, fracture side, AO Foundation and Orthopaedic Trauma Association (AO/OTA) classification, Dorr classification, Singh Osteoporosis Index (SOI), American Society of Anesthesiologists classification (ASA), TAD or fracture reduction patterns in the AP view were noted between the two groups. The negative reduction pattern can strongly predict excessive postoperative sliding (OR 4.286, 95% CI 1.637-11.216, P = 0.003). The incidence of excessive postoperative sliding increased by 8.713-fold when the MFD decreased by 10% (OR 8.713, 95% CI 1.925-39.437, P = 0.005).

CONCLUSIONS

A low medullary filling degree and negative fracture reduction pattern in the lateral view were both independent risk factors for excessive postoperative sliding.

Finite-Element Analysis of a Novel Cephalomedullary Nail for Restricted Sliding to Reduce Risk of Implant Failure in Unstable Intertrochanteric Fractures

Objective

How to restrict sliding of cephalomedullary nail and rigid reconstruct medial support for unstable intertrochanteric fractures remains a challenge. This study aims to explore the feasibility of a novel cephalomedullary nail for restriction sliding and reconstruction of medial femoral support to prevent failure in unstable trochanteric fractures through finite element analysis.

Methods

The DICOM files of a unilateral femur spiral computed tomography (CT) scans from a elderly female were converted into STL files, and the most common clinical trochanteric fracture model with the absence of medial support, AO/OTA 31‐A2.3 was simulated by removing the posterior medial femur. The model of a novel medial sustain nail (MSN‐II) and a widely used nail (proximal femoral nail anti‐rotation PFNA‐II) were modeled according to the manufacturer‐provided engineering drawing. Different loads were applied to the femoral head to simulate the postoperative weight bearing gait. The sliding distance of helical blade in femoral neck, maximum stress of femur and nail, displacement of proximal fragment were analyzed to revealing the mechanical stability of unstable trochanteric fracture stabilized by different implant.

Results

The sliding distance of helical blade in the femoral neck, the maximum stress on the femur and nail, the displacement of proximal fragment in MSN‐II under 2100N axial load were 0.65 mm, 689 MPa, 1271 MPa, 16.84 mm respectively, while that were 1.43 mm, 720.8 MPa, 1444 MPa, 18.18 mm, respectively in PFNA‐II. The difference between the two groups was statistically significant (P < 0.05) and the stress was mainly distributed in medial distal side of nail but helical blade and the proximal aperture for the nail in MSN‐II. Compared to PFNA‐II, MSN‐II demonstrates biomechanical merit against femur medialization, cut‐out and coax varus.

Conclusion

The sliding distance of helical blade in femoral neck, the maximum stress on the femur and nail, and the displacement of proximal fragment of MSN‐II were less than those of PFNA‐II in the treatment of unstable intertrochanteric fractures. Therefore MSN‐II has better stability than PFNA‐II and it may have the potential to avoid femur medialization and cut out. It might be an option in unstable trochanteric fracture because of its superiority in restricted sliding and medial support reconstruction.

Association between Immediate Postoperative Radiographic Findings and Failed Internal Fixation for Trochanteric Fractures: Systematic Review and Meta-Analysis

Failed internal fixations for trochanteric fractures have a strong negative impact owing to increased postoperative mortality and high medical costs. However, evidence on the prognostic value of postoperative radiographic findings for failed internal fixations is limited. We aimed to clarify the association between comprehensive immediate postoperative radiographic findings and failed internal fixation using relative and absolute risk measures. We followed the meta-analysis of observational studies in epidemiology guidelines and the Cochrane handbook. We searched specific databases in November 2021. The outcomes of interest were failed internal fixation and cut-out. We pooled the odds ratios and 95% confidence intervals using a random-effects model and calculated the number needed to harm for each outcome. Thirty-six studies involving 8938 patients were included. The certainty of evidence in the association between postoperative radiographic findings and failed internal fixation or cut-out was mainly low or very low except for the association between intramedullary malreduction on the anteromedial cortex and failed internal fixation. Moderate certainty of evidence supported that intramedullary malreduction on the anteromedial cortex was associated with failed internal fixation. Most postoperative radiographic findings on immediate postoperative radiographs for trochanteric fractures were uncertain as prognostic factors for failed internal fixations.